Update iso_currency requirement from 0.4 to 0.5

Updates the requirements on [iso_currency](https://github.com/zbrox/iso_currency) to permit the latest version.
- [Commits](zbrox/iso_currency@0.4.0...0.5.0)

---
updated-dependencies:
- dependency-name: iso_currency
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>

Cargo.toml

@@ -37,7 +37,7 @@ futures-util = { version = "0.3", default-features = false, features = [
     "sink",
     "std",
 ] }
-iso_currency = { version = "0.4", features = ["with-serde"] }
+iso_currency = { version = "0.5", features = ["with-serde"] }
 zip = "2.1"
 base64 = "0.22"
 google-authenticator = { version = "0.4", optional = true }